Helicopter



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K. WATSON HELICOPTER 2 Sheets-Sheet 1 Filed Dec. 12, 1947 Jane 30, 19% K. WATSON HELICOPTER Filed Dec. 12, 1947 2 Sheets-Sheet 2 a T I! 7 L 14 a l2 l v/ t 0 IE L1,

lime/77? I gaexainbleni. the invention; :constructional Patented Jan. 10, 1950 orrrcs -2HELIGOPEER Kennth watsonj WeNaom -Southampton, lEnglandaass'ignoreto'i'lhe Cierva'Autogiro Company 'rsectmn-nrutne' Law 690,.A1igusrs;1946

:Patentexpires points of a' crown wheel in driving connection :rotate inthetrunnions; and carry pinions l4, l

wi'th themub and the 'driving connections oft-the ipinions withthe coaxial shafts 'are" such that'rotation of the latter in the samesense'causes-op- '--posed*-rotation o'fthe pinions "thus-'"drivingthe crown wheelyrotation df'the pinions in the same *sense,-due to *t'iltingm'f thecrown wheel-about the pinion "axis being 'accommodated 'by--diifer- '-ential-rotation"tif theshafts.

According to a feature of this inventionpone "'of the'coaxi-al shaits isintwo partscoupIed to- *gether through a disengageable 'clutch,-*disengagem'ent'of 'which"a1loWs *both coaxial shafts 'to *idlearid disconnects the "transmission between "-engineand rotor.

In .onetpre'ferre'd form' "of construction," the -co-; :a'xial "shafts are "in the plane "perpendicular to {the tilting axis, "and each drives one of the two pinions'through'bevel-gearingwhich reverses the direction .of rotation of oneof the pinions'with *respetzttfthat of'ithe other when 'th-e'coaxial :shaftswotate the "same "sense. This "gearing is "supported "in a non =r'otative and "non tilting housing ,or bearingstructure embodying trunnions, whichsupportthe pinion shafts and on which the nonr-rotativet-memberof the hub-as-; sembly is tiltably supported.

'- fThe t'coaxial shafts ware preferably directly driven by one and the other"respectivelypf'rtwo sun-pinionsof I the differentialegear, iwhose planets are supported in a cage driven by the engine.

For'better understanding of the invention, "an

*"example ofmechanism in accordance 'with it is jiiliustrated V, in the accompanying drawing, in

"'whic h'l Figure 1""is a central =verticalrsection of a-=rotor huh-assembly and driving transmission;

ta ken' in the plane "containing "the hub' 'tilting faxisrarid in'which "Figure? -is "a vertioal' section through the rotor "hub assembly taken "at "right angles "to the plane "of "Figure 1. This "drawing is entirely conventional;andiwis only intended to .illustrate the essential elements of theselected .detai'ls "*niay be carried "out"in" accordance with' established principles and good engineering practice as well understood by competent engineers.

2 Intheednawing, 1 is a pylon structure rigidly supporting a tubular mast 2 terminating in 1a thousingqor;fork :3'provided with trunnions 4. .The ptrunnionsasupport trunnion bearings 5 on *which :21, non-rotating :hub supporting member -6- can tilt. ,1 The-memberfi'carries bearings! on which irotorahubi8zicarrying rotor blades 9- can rotate about a substantially vertical axis. A crown wheel I9 is provided with a sleeve extension "which risi-free .to rotate ion the 'hub :supporting memberfi-andiis connectedxto thehub 8-by a freez wheel-coupling ll. LTheftr-unnions 4;"also support shafts I2, 13, TWhiChl-iil'e5ICO3;Xia1"Wlth .bearings' 5 and free to nneshing:respectivelywith diametrically opposite points of the crown wheel I0. Shafts l2, 13 also roarry bevelrgears" Hi, I! which respectively mesh 'twith bevel :gears 18, l9 carried respectively'on vertical coaxial shafts 20, 2! which are supported by the fixed mastZ.

'AIigne'd with these shafts isan' engine-driven "shaft- '22 on which is splined an extension of a housing 23 constituting the planetary cageo'fa 'g 'd'ifferential gear whose planet wheels 24 are :meshed witha pair of sun-wheels 25, 26, the "*formerbeing secured to the lower end of shaft 20 and the latter to an extension shaft" 21 'which *is coupled to'shaft 2! through clutch 28.

The torque of the engine shaft 22 is distributed :--b'etween""the"two coaxial shafts 28 and 21 by the "'difierentialgear 23m '26 and, when the clutch 2'8 is-*engagedfthetorque of shaft 2! is transn1'ittedtoshaft2 I. The torques of shafts 2i] and 352i are in the same direction and are transmitted by thegearing i8, l9,'l6, 11, to the shafts I2, '13; the torques in which are in opposed directions intending to rotate'thepinions l4, It in opposite sensessothatboth tend to drive the crown wheel 40 i0 inthe samedirection. As long as thehub- Thisfprevents diiferential' rotation of the: shafts '20an'd2l, ensuring that the engine torqueis requallyvidistributed .by.'.the differential gear lbeitweenlthesestwoishafts. The mechanism there- .forerbiehavesasifthegears lfiiandll were driven 'byasingle shaft, .their-rrotationbeing transmitted by shafts I2, l3 and the pinions I4, I5 to .:the rzcrowniwheelilfl.

-:However, '-"-W1IBIl"-;the 'hubesupporting :member tial displacements are accommodated by the differential gear 23 to 26 in the known manner.

When the clutch 28 is disengaged, thus disconnecting the shaft extension 21' from the shaft 2 l the differential gear becomes free of restraint, rendering the rotor and the engine shaft independent of one another and allowing either or both to rotate freely.

It will be evident that, since rotation is transmitted to the hub by pinions coaxial withthe trunnion axis, about which the hub tilts, the angular velocity of the hub is constant, and independent of the degree of tilt; and further, that owing to the connection of these pinions to the engine shaft through a differential gear, the driving mechanism of the hub imposes no restraint on tilting displacement thereof.

It will also be evident that the torque-reaction of the crown wheel is entirely transmitted through shafts l2, l3 and the trunnions 4 to the fixed structure, and no part of it is transmitted to the member 6 and the hub-tilting controls.

I claim:

1. In an aircraft having a tiltably mounted sustaining rotor, rotor drive mechanism including a gear connected with the rotor, a pair of rotor drive shafts, gearing connecting said shafts with said first gear including pinions arranged coaxially with a rotor tilting axis, and torque equalizing gearing for driving the shafts of said pair in the same direction.

2. A construction according to claim 1 and further including a disconnectible clutch in one of said shafts between the torque equalizing gearing and one of said pinions.

3. In an aircraft having a sustaining rotor, rotor driving mechanism including in combination with a power shaft, a pair of rotor drive shafts, gearing connecting the shafts of said pair with the rotor, torque equalizing gearing connecting the shafts of said pair with the power shaft, and a disconnectible clutch in one of the shafts of said pair between said first and second gearings.

4. In an aircraft having a sustaining, rotor with a hub mounted on a pivot to provide for tilting movement thereof, rotor drive mechanism including a pair of pinions arranged coaxially with the hub mounting pivot, a gear connected with the hub and meshing with said pinions, and

torque equalizing driving means for driving said pinions in opposite directions.

5. A construction according to claim 4 in which the torque equalizing driving means includes a pair of drive shafts geared respectively to said pinions, a power shaft, and differential gearing inter-connecting the power shaft and said pair of shafts.

6. In an aircraft having a tiltably mounted sustaining rotor, rotor drive mechanism comprising in combination with a power shaft, a gear connected with the rotor and tiltable therewith, a pair of rotor drive shafts, gearing connecting said pair of shafts with said first gear, and differential gearing connecting said pair of shafts with said power shaft.

7. In an aircraft having a tiltably mounted sustaining rotor, rotor drive mechanism comprising in combination with a power shaft, a gear connected with the rotor and tiltable therewith, a pair of rotor drive shafts, gearing connecting said pair of shafts with said first gear including pinions arranged coaxially with a rotor tiltin axis, and differential gearing connectingsaid pair of shafts with said power shaft.

8. In an aircraft having a tiltably mounted sustaining rotor, rotor drive mechanism comprising in combination with a power shaft, a gear connected with the rotor and tiltable therewith, a pair-of rotor drive shafts one of which incorporates a disconnectible clutch, gearing connecting said pair of shafts with said first gear, and differential gearing connecting said pair of shafts with said power shaft.

9. In a helicopter having a power-plant and a rotor whose hub is controllably tiltable in one axial plane only, rotor driving transmission mechanism including differential gearing and two 00-- axial shafts driven by the power-plant through the differential gearing, a crown-wheel in driving connection with the hub, and two pinions driven respectively by the shafts, arranged coaxially with the hub-tilting axis and meshing respectively with diametrically opposite points of the crown-wheel, so that rotation of the two shafts in the same sense causes opposed rotation of the pinions and drives the crown-wheel'and hub, but tilting of the hub rotates both pinions in the same sense causing opposed rotation of the shafts, which the differential gearing allows to take place freely.

10. Helicopter transmission mechanism as claimedin claim 9, further including a disengageable clutch, and in which one of the coaxial shafts is driven by the differential gearing through the disengageable clutch.

11. Helicopter transmission mechanism as claimed in claim 9, further including bevel gearing and in which the coaxial shafts are perpendicular to the pinion and hub-tilting-axis and each drives its associated pinion through the bevel gearing.

12. Helicopter transmission mechanism as claimed in claim 11, further including a nonrotative and non-tilting rigid structure supporting the coaxial shafts and bevel gearing and in which said structure is provided with hollow trunnions on which a non-rotative member of the hub-assembly is tiltably mounted and still further in which the trunnions comprise bearings in which the pinions engaging thecrown-wheel are mounted.

13. Helicopter. transmission mechanism .as claimed in claim 9 and further includinga freewheel coupling through which the crown-wheel drives the hub.

- KENNETH WATSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Austria is. 10, 1914 

